In an oil well it is often necessary to seal a section of the annulus between the formation surface and a tubular conduit, or between the casing or liner and a tubular conduit. Packers are widely used to create such a seal.
Conventional packers generally employ a rubber inflatable element which is inflated into engagement with the rock surface or an element which expands under the action of a setting force into engagement with the rock surface.
Conventional packers, however, have associated drawbacks. Once installed a substantial pressure differential can exist across the element, and the inflation or setting pressure applied has to be sufficient to withstand these differential pressures. Due to the level of setting or inflation pressure which is applied to the element to withstand the potential differential pressures, at the point of contact between the seal element and the formation, the formation can be put under a great deal of stress. This stress can cause the rock to fail. Failure of the rock may require that the packer be moved and reset at a different location.
Furthermore, particularly with inflatable packers, the differential pressure can result in movement of the element, which, in turn, can cause mechanical wear, resulting in damage to the element. In the case of an inflatable element, such damage can permit a liquid inflation medium to leak out.
It is an object of the present invention to obviate or mitigate at least one of the aforementioned disadvantages.